The purpose of this study is to compare the in vitro cytotoxicity tests according to the ISO 10993-5 (2009) standards using direct contact and the test on liquid extracts of compounds previously identified as possible toxic impurities in perfluorocarbon liquids (PFCLs) for use in vitreoretinal surgery. Compounds including perfluorooctanoic acid (PFOA), 1H-perfluorooctane (1H-PFO), 2H-tridecafluoro-2-methylpentane, 1H,2H-octafluorocyclopentane, and 2H,3H-decafluoropentane were analyzed by ¹⁹F NMR before and after extraction using an aqueous solution and tested by both the direct contact and liquid extract tests in L929, BALB 3T3, and ARPE-12 cells. The concentration that reduced in vitro cell viability by 30%, the cytotoxicity concentration threshold (CC₃₀), was determined for each compound. ¹⁹F NMR spectroscopy confirmed the immiscibility of perfluoro-n-octane (PFO) and 1H-PFO and the solubility of PFOA with the extraction vehicle. The other samples reacted with the extraction vehicle, releasing fluoride ions. Using the direct contact test, the CC₃₀ of PFOA, 1H-PFO, 2H-tridecafluoro-2-methylpentane, 1H,2H-octafluorocyclopentane, and 2H,3H-decafluoropentane corresponded to 48 124, 50, 14, 8035, and 46 ppm, respectively. The method on liquid extracts did not detect cytotoxicity in three out of five tested compounds, and CC₃₀ could not be determined. In conclusion, the in vitro cytotoxicity test by direct contact revealed a positive correlation between cell toxicity and the concentration of the tested substance. Conversely, the test on liquid extracts hardly detected the cytotoxicity of toxic impurities in PFCLs. Thus, only the cytotoxicity test by direct contact, according to ISO 10993-5 (2009), is a sensible and reliable method to detect possible cytotoxic impurities in PFCLs to guarantee patient safety.

Abstract
Serious intraocular toxicity cases have been reported worldwide after the use of different perfluorocarbon liquids. The current study reports for the first-time the clinical pictures of cases of acute intraocular toxicity caused by MEROCTANE, a perfluoro-octane commercialized by a Turkish company and distributed in many countries. A series of 18 cases from Chile and Spain was retrospectively analysed. To evaluate the impurity profile, a suspicious MEROCTANE sample (lot OCT.01.2013) was analysed by gas chromatography mass spectrometry and compared with a non-suspicious sample of the same commercial perfluoro-octane (lot OCT 722011). Cytotoxicity was tested following a direct-contact method, taking into consideration the high volatility and hydrophobicity of perfluoro-octane and following the ISO 10993 guideline. Cytotoxicity test showed clear cytotoxic effects of the analysed batch (less than 9% of cell viability). Moreover, chemical analysis demonstrated the presence of many contaminants, some highly toxic (acids and alcohols). Perfluorocarbon liquids are useful tools for intraocular surgery but companies and Agencies of Medical Devices must implement measures that guarantee the safety of these products based on both chemical and cytotoxicity analysis for every batch. Medical staff should be encouraged to report any suspected case to their respective National Agencies.

Purpose: To compare two commercially available staining solutions (MembraneBlue Dual® by D.O.R.C., Netherlands, and TWIN by AL.CHI.MI.A. S.R.L., Italy), in terms of intraoperative handling, staining efficacy and safety, in eyes undergoing surgery for idiopathic epiretinal membrane (ERM).

Methods: In this observational cross-sectional study, the performance of the dyes used during the procedure (cohesion, ERM and internal limiting membrane [ILM] staining efficacy) was scored by the surgeon using a customized questionnaire after 10 procedures with each of the two dyes. Best-corrected visual acuity (BCVA), central foveal thickness (CFT), blue-light fundus autofluorescence (BAF), and microperimetry-determined retinal sensitivity were reviewed preoperatively and then at 1 and 3 months after surgery.

Results: ILM staining efficacy with TWIN was scored 2.89 ± 0.33 by the surgeons, which turned out to be higher than with MembraneBlue Dual® (1.90 ± 0.31, P = 0.0002). The cohesion score was 2.70 ± 0.48 for TWIN and resulted significantly higher than with MembraneBlue Dual® (1.60 ± 0.51, P = 0.0010). BCVA, CFT and retinal sensitivity were similar in the two groups, 1 and 3 months postoperatively (P nonsignificant for all).

Conclusions: Both TWIN and MembraneBlue Dual® dyes showed suitable staining properties and equivalent safety and efficacy profiles, both intra- and postoperatively. The TWIN dye might offer a solution for surgeons who prefer a more cohesive and stable dye.

This study aimed to assess the cytotoxic effect of low molecular weight components (LMWC) and conventional silicone oils (SOs) 1000 cSt with different degree of purification (raw, intermediate, and purified) using in vitro cytotoxicity tests. Direct contact cytotoxicity tests were performed in BALB 3T3 and human retinal pigment epithelial cells (ARPE-19) using quantitative and qualitative evaluation according to the ISO 10993-5 (2009) standards. Conventional SOs 1000 cSt in form of raw, intermediate (intermediate product obtained during distillation process), and purified SO (final product after distillation) and a concentrate of LMWC (including siloxane chains with molecular weight up to 1557 g/mol) were directly applied to 100% of cell layer area for 24 h. Cell viability was quantified using 3-(4,5-dimethylthiazole-2-yl)-2,5–28 diphenyltetrazolium bromide (MTT) and neutral red uptake assays in ARPE-19 and BALB3T3, respectively. All tested samples, including the concentrate of LMWC, resulted to be not cytotoxic according to ISO 10993-5 in both qualitative and quantitative evaluations. However, the cellular viability was significantly higher in the intermediate and purified SO compared with the raw SO in ARPE-19 cells. No reduction in cell viability was detected by LMWC.

The absence of cytotoxicity was observed for all tested samples in both BALB3T3 and ARPE-19 after 24 h of application. A direct cytotoxic effect is not likely to be involved in the potential complications related to SO and LMWC. Long-term potential adverse effects of SO could be related to the raw material and to different concentrations of LMWC.

Purpose: To provide useful guidelines, targeted at ophthalmology professionals, to minimize COVID-19 infection of both health-care workers and patients.

Methods: In this review we present updated literature merged with our experience from hospitals in Bergamo, the epicenter of the COVID-19 European outbreak.

Results: Non-pharmaceutical interventions, hygienic recommendations and personal protective equipment to contain viral spread as well as a suggested risk assessment for postponement of non-urgent cases should be applied in ophthalmologist activity. A triage for ophthalmic outpatient clinic is mandatory.

Conclusion: Ophthalmology practice should be reorganized in order to face COVID-19.

Purpose: To validate the cytotoxicity test of perfluorocarbon liquids (PFCLs) for intraocular use according to the ISO 10993-5 standard.

Methods: BALB/3T3, ARPE-19 cell lines, and 3-mm human retina ex vivo samples were cultured in 96-well plates. Contact areas of 22%, 59%, and 83% and 2.5-, 12-, and 24-hour contact times were tested in cell lines. Cell viability was quantified by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in ARPE-19 and neutral red uptake (NRU) viability assay for BALB/3T3. Apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay in ARPE-19 cells. 1-H perfluorooctane (1H PFO) and purified perfluorooctane (PFO) were used as cytotoxic and not cytotoxic controls, respectively. Cell viability was assessed by MTT assay in retina ex vivo samples.

Results: Qualitative evaluation showed that cytotoxic control induced apoptosis, severe reactivity zones, and cytotoxicity according to ISO 10993-5 in all tested conditions. Quantitative evaluation of 1H PFO showed no cytotoxicity according to ISO 10993-5 on 22% areas, whereas cytotoxicity was detected on 59%, and 83% contact areas. The PFO was confirmed not to be cytotoxic in all tested conditions.
Quantitative evaluation in retina ex vivo samples confirmed no cytotoxicity with PFO and cytotoxicity with 1H PFO.

Conclusions: The direct contact cytotoxicity test according to ISO 10993-5 is a suitable method to detect the cytotoxicity of PFCLs and was validated using
quantitative and qualitative approaches in ARPE-19 and BALB/3T3 cells covering 59% of the cell surface areas for 24 hours.

Translational Relevance: Direct contact cytotoxicity test using specific conditions was validated, whereas different test conditions could not be validated.